Effects of fasting on growth hormone, growth hormone receptor, and insulin-like growth factor-I axis in seawater-acclimated tilapia, Oreochromis mossambicus

Fox, Bradley K.; Riley, Larry G.; Hirano, Tetsuya; Grau, E. Gordon

doi:10.1016/j.ygcen.2006.04.007

Cited by 79 publications

(45 citation statements)

References 41 publications

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“…In an alternative form of Gh resistance seen during feeding manipulation, plasma Gh increases and hepatic igf1 gene expression declines with no change in hepatic ghr mRNA (Fox et al 2006, raising the possibility that Ghr signaling may be impaired (Beauloye et al 2002). In our investigation, hepatic ghr1 and ghr2 mRNA levels declined during feed deprivation along with hepatic igf1 mRNA and circulating Igf1 peptide.…”

Section: Discussionmentioning

confidence: 55%

Regulation of endocrine and paracrine sources of Igfs and Gh receptor during compensatory growth in hybrid striped bass (Morone chrysops×Morone saxatilis)

Picha

Turano

Tipsmark

et al. 2008

Journal of Endocrinology

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Compensatory growth (CG) is a period of growth acceleration that exceeds normal rates after animals are alleviated of certain growth-stunting conditions. In hybrid striped bass (HSB, Morone chrysops!Morone saxatilis), 3 weeks of complete feed restriction results in a catabolic state that, when relieved, renders a subsequent phase of CG. The catabolic state was characterized by depressed levels of hepatic Type I and II GH receptor (ghr1, ghr2) and igf1 mRNA, along with considerable decreases in plasma Igf1. The state of catabolism also resulted in significant declines in hepatic igf2 mRNA and in circulating 40 kDa Igfbinding protein (Igfbp). Skeletal muscle expression of ghr2 mRNA was significantly increased. Upon realimentation, specific growth rates (SGRs) were significantly higher than sized-matched controls, indicating a period of CG. Hepatic ghr1, ghr2, igf1 and igf2 mRNA levels along with plasma Igf1 and 40 kDa Igfbp increased rapidly during realimentation. Plasma Igf1 and total hepatic igf2 mRNAwere significantly correlated to SGR throughout the study. Skeletal muscle igf1 mRNA also increased tenfold during CG. These data suggest that endocrine and paracrine/autocrine components of the GH-Igf axis, namely igf1, igf2, and ghr1 and ghr2, may be involved in CG responses in HSB, with several of the gene expression variables exceeding normal levels during CG. We also demonstrate that normalization of hepatic mRNA as a function of total liver production, rather than as a fraction of total RNA, may be a more biologically appropriate method of quantifying hepatic gene expression when using real-time PCR.

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Section: Discussionmentioning

confidence: 55%

Regulation of endocrine and paracrine sources of Igfs and Gh receptor during compensatory growth in hybrid striped bass (Morone chrysops×Morone saxatilis)

Picha

Turano

Tipsmark

et al. 2008

Journal of Endocrinology

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“…It has been reported in gilthead sea bream and black sea bream that the mRNA level of GHR1 in the liver decreased after starvation (Saera-Vila et al 2005;Deng et al 2004). In mozambique tilapia, starvation fails to affect the expression of GHR1 in the liver (Pierce et al 2007;Fox et al 2006). Similarly to GHR1, variability in GHR2 expression in liver exists among species and experiments.…”

Section: Discussionmentioning

confidence: 99%

Identification and expression analysis of two growth hormone receptors in zanzibar tilapia (Oreochromis hornorum)

Gao

et al. 2010

Fish Physiol Biochem

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Growth hormone plays important roles in various physiological processes such as growth, metabolism, and reproduction. In this study, two cDNAs encoding growth hormone receptor (GHR) were isolated from the liver of zanzibar tilapia (Oreochromis hornornum). The two cDNAs were 2,831 and 2,044 bp in length and named GHR1 and GHR2, respectively. GHR1 and GHR2 shared 57.4% similarity in nucleotide sequences and 33.5% similarity in deduced amino acid sequences. Consequently, it was presumed that they were two different genes. Conserved regions of GHR1 and GHR2 in zanzibar tilapia were different from those of other vertebrates. For example, conserved box2 regions of GHR1 and GHR2 in zanzibar tilapia were, respectively, WVELM and WVEFT, while it was WVEFI for GHRs in other vertebrates. Similar to other fish species, GHR1 and GHR2 were expressed in brain, gill, liver, muscle, spleen, gonad, stomach, kidney, and pituitary in zanzibar tilapia. The expression levels were the highest in liver. Unlike fathead minnow (Pimephales promelas) and mossambique tilapia (O. mossambicus), the expression levels of GHR1 in most female fish tissues were higher than those in male fish. No significant difference in GHR2 expression was found in all the tissues in male and female of zanzibar tilapia. Under fasting condition, the expressions of GHRs and IGF-II were significantly up-regulated (P < 0.05) in liver, while the expression of IGF-I remained stable. This observation would contribute to understanding the evolution of the GHR family in further investigation of growth regulation of zanzibar tilapia.

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“…In teleosts as in most other vertebrates (human, sheep, dogs, chickens, but not rats), food deprivation causes significant elevation of plasma GH concentrations [salmonids: [29,30,31,32]; eel: [33]; sea bream: [34]; tilapia: [35, 36]]. In this regard, most species models are applicable to the human with the obvious exception being rats [for review, see [37]].…”

Section: Gh Regulation Of Growth and Metabolismmentioning

confidence: 99%

“…Some authors suggest that this growth arrest is primarily due to a decline in the production of IGF1 [for review, see [92]]. Indeed, nutrition is another major regulator of IGF1, as food deprivation causes reduction of circulating levels [rainbow trout: [93]; coho salmon: [94]; tilapia: [36]; [95]; chinook salmon: [31]; channel catfish: [96]] and mRNA levels [eel: [97]; coho salmon: [29]; barramundi: [98]; Chinook salmon: [31]; channel catfish: [96]; grouper: [99]; tilapia: [36]] of IGF1. The starvation-induced increase in plasma GH could be due to a reduced IGF1 feedback on the pituitary resulting, in turn, from a reduction in hepatic GH receptor (GH-R) [coho salmon: [100]; salmon: [29]; masu salmon: [101]; black seabream: [102]].…”

Section: Regulators Of Gh Involved In Energy Balancementioning

confidence: 99%

“…The starvation-induced increase in plasma GH could be due to a reduced IGF1 feedback on the pituitary resulting, in turn, from a reduction in hepatic GH receptor (GH-R) [coho salmon: [100]; salmon: [29]; masu salmon: [101]; black seabream: [102]]. However, other recent studies showed that starvation did not induce changes in hepatic GH-R expression [tilapia: [36]; rainbow trout: [32]], suggesting post-receptor mechanisms of resistance to GH. Compared with rats [37], a much longer period of starvation is required to observe significant changes in IGF1 levels in fish and this slower response may be a reflection of the generally slower metabolism of ectothermal animals [29].…”

Section: Regulators Of Gh Involved In Energy Balancementioning

confidence: 99%

See 1 more Smart Citation

Comparative Aspects of GH and Metabolic Regulation in Lower Vertebrates

Rousseau

Dufour

2007

Neuroendocrinology

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In all vertebrates, the regulations of growth and energy balance are complex phenomena which involve elaborate interactions between the brain and peripheral signals. Most vertebrates adopt and maintain a life style after birth, but lower vertebrates may have complex life histories involving metamorphoses, migrations and long periods of fasting. In order to achieve the complex developmental programs associated with these changes, coordinated regulation of all aspects of energy metabolism is required. Somatotropic axis (somatostatin (SRIH) growth hormone (GH) and insulin-like growth factor 1 (IGF1), is known to be involved in the regulation of growth and energy balance. Interestingly, recent studies showed that additional factors such as pituitary adenylate cyclase-activated polypeptide (PACAP), corticotropin-releasing hormone (CRH), ghrelin and leptin could also have major roles in the control of growth and metabolism in lower vertebrates (fish, amphibians and reptiles). This mini-review will survey the function of GH and metabolic regulation in lower vertebrates.

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Effects of fasting on growth hormone, growth hormone receptor, and insulin-like growth factor-I axis in seawater-acclimated tilapia, Oreochromis mossambicus

Cited by 79 publications

References 41 publications

Regulation of endocrine and paracrine sources of Igfs and Gh receptor during compensatory growth in hybrid striped bass (Morone chrysops×Morone saxatilis)

Regulation of endocrine and paracrine sources of Igfs and Gh receptor during compensatory growth in hybrid striped bass (Morone chrysops×Morone saxatilis)

Identification and expression analysis of two growth hormone receptors in zanzibar tilapia (Oreochromis hornorum)

Comparative Aspects of GH and Metabolic Regulation in Lower Vertebrates

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